Modeling Branch Characteristics In Douglas-fir & Western Hemlock.
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Modeling Branch Characteristics In Douglas-fir & Western Hemlock
Cast of Characters Dr. Gero Becker –Professor, Univ. of Freiburg, Germany, Visiting Scholar, SMC Dr. David Briggs –Professor UW CFR, Director, SMC Dr. Olav Hoibo –Associate Professor, Agric. Univ. Norway, Visiting Scholar, SMC Eric Turnblom –Assistant Professor, UW CFR, Silviculture Project Leader, SMC
Outline I.Number & Diameter of BH Branches: SMC Protocol A.Type I Douglas-fir: PCT Effect on Average BH Branches in a Stand B.Type I Douglas-fir: PCT Effect on BH Branches of Individual Trees C.Type I Western Hemlock: PCT Effect, status D.Type III: Effect of Initial Spacing, status II.PNW/Germany Cross-Comparison of DF Branch Diameter III.Vertical Branch Profiles: DF & WH Live/dead transition Branch/Stem Growth Dynamic
I. Number & Diameter of BH Branches Douglas-fir branch protocol Type I and Type III Installations Taken on height trees on each plot (~42 trees) First whorl above BH –Diameter of largest branch in the whorl –Total # branches in whorl >= 1/2 diameter of largest branch –Total # branches in half-internode above & below the whorl that are >= 1/2 diameter of largest whorl branch
A. Effect of PCT on Douglas-fir: Stand Level Models Sample –19 Type I installations –57 plots ISPA, ISPA/2, ISPA/4 –2397 trees Site Index is Flewelling (2001)
A. Effect of PCT on Douglas-fir: Stand Level Modeling Method a.Factorial Treatment Structure 4 levels of Flewelling Site Index 3 levels of stand density (stems/acre) Covariates: Crown length, crown ratio Mean height, HT_40, mean height above BH Total age, BH age QMD, relative density b.Plots with crown base BH, and combined No differences found with crown base below vs above BH Elapsed time since crown receded above BH is too short
1. Effect of PCT on Total BH Branch Count of Type I Douglas-fir Stands: Results as stems per acre increases total BH branch count decreases more shade on BH branches in denser stands 250 & 550 spa classes are not significantly different 125 spa class is significantly different
1. Effect of PCT on Total BH Branch Count of Type I Douglas-fir Stands: Results Site classes I, II, & III are not significantly different Site IV is significantly lower fewer resources to produce and maintain branches Also, total BH branch count –Decreases as average crown length of stand increases (more shade on BH branches ?) –Decreases as total stand age increases (self pruning?)
2. Effect of PCT on BH Nodal Branch Count of Type I Douglas-fir Stands: Results Site classes II & III are not significantly different Site classes II & IV are not significantly different Highest site class has about 1 more nodal branch (more resources for nodal branch production & survival?)
3. Effect of PCT on BH Internodal Branch Count of Type I Douglas-fir Stands: Results Site classes II, & III are not significantly different Site III, I, & IV are not significantly different Site IV low due to fewer resources for production & survival of internodal branches Site I low due to competition and shading by more numerous nodal branches Also, BH internodal branch count –Decreases as average crown length of stand increases (more shade on BH internodal branches ?) –Decreases as total stand age increases (self pruning of internodals?)
4. Effect of PCT on BH Branch Count of Type I Douglas-fir Stands: Regression Models Total = f (ave crown length, stems/acre, total age, site index) Internodal = f (ave crown length, total age, site index) Nodal = Total - Internodal
5. Effect of PCT on Largest BH Branch Diameter of Type I Douglas-fir Stands: Regression Models All significantly different Lower stand density has larger BH branches (more space, less shade on BH, longer lived faster growing branches) Also, largest BH branch diameter –Increases as QMD increases (bigger tree allometry?) –Decreases as total stand age increases (point of maximum branch diameter becomes embedded inside the stem
6. Effect of PCT on Largest BH Branch Diameter of Type I Douglas-fir Stands: Regression Model Average for Stand = f(QMD, total age, stems per acre)
B. Effect of PCT on Douglas-fir: Individual Tree Modeling Method a.Allometry with orthogonal quadratic polynomials for each of the 57 plots Largest BH branch diameter vs other tree size measures: DBH best Branch counts vs other tree size measures: DBH best b.ANCOVA of 57 sets of coefficients 4 levels of Flewelling Site Index 3 levels of stand density (stems/acre) Covariates: Crown length, crown ratio Mean height, HT_40, mean height above BH Total age, BH age QMD, relative density c.Plots with crown base BH, and combined No differences found with crown base below vs above BH Elapsed time since crown receded above BH is too short d.Regression
1. Effect of PCT on BH Branch Counts of Douglas-fir Trees: Regression Model Total = f(DBH, stems per acre, total age, site index, crown length) Internodal: use stand level model = f(total age, site index, crown length) Nodal = Total - Internodal
2. Effect of PCT on Largest BH Branch Diameter of Douglas-fir Trees: Regression Model Individual Tree Largest BH Branch Diameter = f(DBH; stems per acre, total age, QMD, crown length)
3. Conclusion: PCT of Douglas fir (Type I) Stand level variables (red) greatly improved individual tree model predictions! O. Hoibo has also found this in his crown profile research Status: –Article in review with Forest Science Future –Can we relate the BH results to the rest of the tree –Can we develop a QC tool & prediction system that can be related to log grades/sorts
C. Effect of PCT & Planting Density: W. Hemlock Protocol & Plans Type I and Type III Installations Taken on height trees on each plot (~42 trees) 3 foot zone centered on BH –Diameter of largest branch –Total # branches >= 1/2 diameter of largest branch Started in 00/01 Field Season Preliminary analysis after 01/02 season 3 ft
D. Effect of Planting Density: Douglas-fir Type III Data for 98/99, 99/00, 00/01, 01/02 seasons Preliminary work with 98/99 data –8 installations; 6 plots each –small trees on wider spacings tend to have larger branches than same age, larger trees on denser spacings –another aspect of crossover effect? Will begin analysis this winter/spring
II. PNW/Germany Cross-Comparison of DF Branch Diameter Objectives: Determine differences between branch diameter profile characteristics between two geographically disparate (Germany/PNW U.S.) Douglas-fir data sets Gain insights into “best” modeling approach for future branch diameter modeling
Available Data German data set –4 plots: density ranges 150 -300 SPA; sites range 100 -140 ft@50 yr; total ages range 32 -41 years –42 trees: DBH ranges 9.4 -16.1 in.; total heights range 62 -89 ft; HCB ranges 25.6 -47.6 ft. SMC ‘Crown Study’ data set –66 plots:density ranges 80 -600 SPA; sites range 80 -140 ft@50 yr; total ages range 9 -36 years –562 trees:DBH ranges 1.0 -18.3 in.; total heights range 7.4 -104.7 ft; HCB ranges 0 -67.1 ft.
Testing Equations Wobst/Becker Equation: Maguire, et al. (1999) Equation:
Branch Diameter Profile Comparison Upper curve (red) is Wobst/Becker model Lower curve (maeve) is Maguire et al. Upper is for live/dead branches, lower is for live only
Residuals Comparison On average, Maguire et al. predicts larger branches, but...
Future Plans Use both models to predict branch diameters on trees in the SMC data set Determine which modeling approach / equation form is “best” Report results at IUFRO conference 2002
III. Vertical Branch/Knot Profiles: DF Douglas-fir Sample –SMC Type I –High Site, Medium Site –ISPA, ISPA/2 –Similar age & ISPA –1 tree from each septile of DBH distribution (28 total trees) –7 trees x 4 plots = 28 trees –Whorl 3, 6, 9, … 21 from top = 7 whorls/tree
A. Transition from Live to Dead Knot: DF Branch Measurements –Azimuth –Horizontal distance from cambium to Pith Live/dead transition –Knot diameter at Live/dead transition Cambium 1 branch diameter distance from stem surface (outside bark) –All branches Data collected & analysis underway
B. Relationship Between Stem & Branch Diameter Growth Measure –Smallest, median & largest of the 7 tree sample from each plot –Whorl # 6, 12, 18 from top –Annual ring widths of stem cross-section –Annual ring widths of smallest, median, & largest branch in each Data collected & analysis underway
C. Vertical Branch/Knot Profiles: W. Hemlock Sample –Medium Site Type I Hemlock –ISPA & ISPA/2 –1 tree/septile of DBH distribution = 14 total trees –3 foot sections @ mid-live crown, live crown base, midway from crown base to ground, and at BH Transition from sound (live) to unsound (dead) knot –Sound knot length from pith –Knot diameter (max) at transition –Largest 5 and next to smallest branch = 6 total Ring growth of stem & branch: all stem sections (4/tree) –Ring widths of stem –Ring widths of largest, median, & smallest branch Samples collected: Anyone want a job?